1. Field of the Invention
The present invention relates to a thermosensitive multiple recording sheet in which the other base material is removably attached to the side of a thermosensitive recording layer of a thermosensitive recording sheet comprising a base material and the thermosensitive recording layer formed on one surface of the base material through a temporary adhesive layer.
Also the present invention relates to a thermosensitive recording material and, particularly, to a method for producing a thermosensitive multiple recording sheet in which thermosensitive recording and thermosensitive copying are simultaneously conducted.
2. Description of Related Art
A thermosensitive recording system is used in various fields because of the following features: requiring no development; paper quality close to that of a plain paper when using a paper as a substrate; easy to handle; high color developing density; simple recording apparatus; downsizable and cheap; no noise during recording; and capable of simultaneously recording plural sheets. Particularly, the feature capable of simultaneously recording plural sheets is a feature which is excellent as compared with other recording systems such as inkjet and electrophotography, and therefore the thermosensitive recording system is widely used in the fields, such as receipts, slips and memos, where it is required to simultaneously record plural sheets. Particularly, in case of a rolled multiple sheet such as receipt used in a cash register for a supermarket, since a portable recording apparatus is required, the thermosensitive recording system is required.
A conventionally known thermosensitive multiple recording sheet is generally obtained by the following three kinds of systems.    (1) Thermally Sensitive Recording Sheet Superposition System
Thermally sensitive multiple recording sheets obtained by superposition or temporary adhesion of an upper thermosensitive recording sheet and a lower thermosensitive sheet are known (Japanese Unexamined Patent Application, First Publication No. Sho 49-73144 (Claims), Japanese Unexamined Patent Application, First Publication No. Sho 49-98640 (Claims), Japanese Unexamined Patent Application, First Publication No. Sho 49-133041 (Claims), Japanese Unexamined Patent Application, First Publication No. Sho 50-160048 (Claims) and Japanese Unexamined Patent Application, First Publication No. Sho 50-14351 (Claims)).    (2) Colored Ink Thermal Transfer Combined System
There is known a thermosensitive multiple recording sheet in which a thermosensitive color developing layer containing both components of two-component color couplers capable of reacting with heating to develop a color is formed on the surface of a substrate and a thermofusible ink containing, as main components, a thermofusible wax and a coloring material such as carbon black is coated onto the back surface of the substrate and thus the thermofusible ink can be transferred onto the lower sheet to obtain a copy (Japanese Unexamined Patent Application, First Publication No. Sho 52-115229 (Claim 1)).    (3) Reactive Thermal Transfer Combined System
There are known thermosensitive multiple recording sheets obtained by producing an upper recording sheet comprising a substrate, a thermosensitive color developing layer containing both components of two-component color couplers capable of reacting with heating to develop a color formed on the surface of the substrate, and a thermofusible transfer layer containing one component A of two-component color couplers (refereed to as A and B) as a main component coated onto the back surface of the substrate; producing a lower recording sheet comprising a substrate and a transfer receiving recording layer containing the other component B as a main component coated onto the substrate is produced; and laminating the upper recording sheet with the lower recording sheet so that the thermofusible transfer layer of the upper recording sheet and the transfer receiving recording layer of lower recording sheet face with each other (Japanese Unexamined Patent Application, First Publication No. Sho 48-47844, Japanese Unexamined Patent Application, First Publication No. Sho 50-68143, Japanese Unexamined Patent Application, First Publication No. Sho 54-1041 and Japanese Unexamined Patent Application, First Publication No. Sho 57-12693)
Like receipts, detailed payroll sheets, various notifications and medical check-up results notifications, for example, there is generally used an information recorded matter in which disclosed information capable of being confirmed by any one is recorded on the surface of a multiple sheet and confidential information is recorded inside.
In case of the multiple sheet used in the information recorded matter, it is required that disclosed information is recorded on the surface so as to improve recording efficiency and also information different from the disclosed information can be recorded inside.
In such a case, a multiple sheet of a reactive thermal transfer combined system described above and a multiple sheet of a pressure-sensitive recording system with the same constitution are mainly used at present (for example, refer to Registered Utility Model No. 3,046,499).
Since thermosensitive multiple recording sheets obtained by (2) the colored ink thermal transfer combined system and (3) the reactive thermal transfer combined system can not be laminated before recording, principally, (when laminated previously before recording, there arise a problem that the lower recording sheet is stained and the paste used for lamination inhibits transfer of the thermofusible ink or the thermofusible transfer layer of the upper recording sheet, and thus recording density is drastically decreased), it is difficult to form into a rolled sheet and therefore it is obliged to form into a strip shape by point or partial adhesion of lamination ends of two sheets, thus resulting in poor productivity and cost up. Also in case of the recording apparatus, there arose a problem that it is difficult to dispose a mounting tray of the sheet before recording and to perform continuous printing, and therefore it is obliged to use an exclusive printer.
Under these circumstances, the present inventors have taken notice of the thermosensitive multiple recording sheet obtained by (1) the thermosensitive recording sheet superposition system and studied so as to improve the thermosensitive multiple recording sheet.